1. Field of the Invention
The present invention relates generally to device recognition and, more particularly, methods of and systems for recognizing that multiple remote devices are likely under common control and operation.
2. Description of the Related Art
Device fingerprinting (also known as device recognition) is a technology which assigns a unique identifier based on a device's software and hardware settings. This identification technique is attractive because of its adaptability to any device—even where cookies have failed—including PCs, mobile devices, set top boxes, and game consoles.
Device fingerprinting is used to improve on-line advertisement targeting, reduce click fraud, personalize website experiences, and enable multi-channel attribution. While device fingerprinting can identify individual devices, there is currently no accurate way to determine that two or more devices are under common control and operation, e.g., of the same household.
Consider the computer network shown in FIG. 1, which depicts a sampling of typical connections of computing devices to a wide area network (WAN), i.e. the Internet cloud. The connections are made possible by an Internet Service Provider (ISP), which assigns an IP address to each subscriber connected to the network, for example, through a DSL or cable modem. The diagram shows that the subscriber at 100 Main Street is assigned the IP address 77.264.195.10, the public library is assigned the IP address 77.264.198.17, the City Hall is assigned IP address 88.157.64.171, and the subscriber at 2505 Wagonwheel Street is assigned IP address 88.157.64.100. Three of these subscribers have configured a local area network (LAN1, LAN2 and LAN3, as shown) through the use of a router. Downstream of each router are the computing devices residing within each respective LAN. Each such device is expected to share the same WAN IP address, but its location will be differentiated from all others according to its LAN IP address.
A problem arises, however, when attempting to remotely identify devices that belong to the same household, because IP addresses are not static. That is because the entity assigning IP addresses—whether the ISP or the LAN administrator—typically assigns them for a finite period, known as a lease time. Lease time periods typically vary, and may be granted on the order of hours, days, months, or longer, according to the preference of the administrator. Therefore the population of computing devices associated with a particular LAN may share a common WAN IP address on one day, but share another WAN IP address the following day.
To make matters worse, an ISP may rotate an available pool of WAN IP addresses among its many subscribers, such that computing devices in different households could be accessible through identical WAN IP addresses during different parts of the day. For example, from 8 AM to noon, IP address 77.264.195.10 may be assigned to the LAN 1 subscriber and associated with each of its computing devices, and later that same day from noon to 4 PM the same IP address may be assigned to the LAN 2 subscriber and associate with each of its computing devices.
The same problem of rotating IP addresses according to lease time expiration can also occur at the LAN level. As in the WAN case, the rules governing assignment of the LAN IP address are typically configurable by the administrator. Although this does not affect the determination whether a particular computing device exists within an identified household, it emphasizes that, due its transience, the LAN IP address is unsuitable for use as an identifier for purposes of reliably fingerprinting a device.
What is needed is a more reliable way to accurately determine whether two or more devices are under mutual control and operation.